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EPITHERMAL GOLD-SILVER MINERALIZATION RELATED TO VOLCANIC SUBSIDENCE IN THE CUSTER GRABEN, CUSTER COUNTY, IDAHO.

Journal of Geochemical Exploration

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Abstract

The Custer graben is a 13 by 32 km northeast-trending volcano-tectonic graben in the Challis volcanic field of central Idaho. Andesites, rhyolites, and associated pyroclastic rocks host vein and disseminated gold-silver deposits that are localized along discrete northeast- and northwest-trending fracture zones. Ore minerals in vein deposits are electrum, native gold and silver, chalcopyrite, and various sulfosalts in a gangue of pyrite and fine-grained quartz. At the Sunbeam Mine, near the center of the graben, vein and disseminated gold-silver mineralization occurred in hydrothermally altered rhyolite and pyroclastic rocks. The host rock has been pervasively silicified, and the feldspars altered to clay minerals. Analyses of surface and drill-core samples show that altered rocks are variably enriched in gold, silver, molybdenum, arsenic, zirconium, and selenium. Intense silicification is shown by SiO//2 values at high as 93%.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
EPITHERMAL GOLD-SILVER MINERALIZATION RELATED TO VOLCANIC SUBSIDENCE IN THE CUSTER GRABEN, CUSTER COUNTY, IDAHO.
Series title:
Journal of Geochemical Exploration
Volume
25
Issue:
1-2
Year Published:
1984
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geochemical Exploration
First page:
247
Last page:
248
Conference Title:
Explor for Ore Dep of the North Am Cordillera, Sel Pap of the Symp of the Assoc of Explor Geochem
Conference Location:
Reno, NV, USA
Conference Date:
25 March 1984 through 28 March 1984